Characterizing Hypertension Specialist Care in Canada: A National Survey

Background The hypertension specialist often receives referrals of patients with young-onset, severe, difficult-to-control hypertension, patients with hypertensive emergencies, and patients with secondary causes of hypertension. Specialist hypertension care compliments primary care for these complex patients and contributes to an overall hypertension control strategy. The objective of this study was to characterize hypertension centres and the practice patterns of Canadian hypertension specialists. Methods Adult hypertension specialists across Canada were surveyed to describe hypertension centres and specialist practice in Canada, including the following: the patient population managed by hypertension specialists; details on how care is provided; practice pattern variations; and differences in access to specialized hypertension resources across the country. Results The survey response rate was 73.5% from 25 hypertension centres. Most respondents were nephrologists and general internal medicine specialists. Hypertension centres saw between 50 and 2500 patients yearly. A mean of 17% (± 15%) of patients were referred from the emergency department and a mean of 52% (± 24%) were referred from primary care. Most centres had access to specialized testing (adrenal vein sampling, level 1 sleep studies, autonomic testing) and advanced therapies for resistant hypertension (renal denervation). Considerable heterogeneity was present in the target blood pressure in young people with low cardiovascular risk and in the diagnostic algorithms for investigating secondary causes of hypertension. Conclusions These results summarize the current state of hypertension specialist care and highlight opportunities for further collaboration among hypertension specialists, including standardization of the approach to specialist care for patients with hypertension.


R ESUM E
Contexte : Le sp ecialiste de l'hypertension reçoit souvent des patients orient es pour une hypertension s evère, d'apparition pr ecoce et difficile à maîtriser, pour une urgence hypertensive ou pour des causes secondaires de l'hypertension.Les soins sp ecialis es de l'hypertension complètent les soins primaires pour ces cas complexes et font partie d'une strat egie globale de maîtrise de l'hypertension.Cette etude avait pour objectif de caract eriser les centres de traitement de l'hypertension et les habitudes de pratique des sp ecialistes canadiens qui CJC Open 5 (2023) 907e915 https://doi.org/10.1016/j.cjco.2023.08.014 2589-790X/Ó 2023 The Authors.Published by Elsevier Inc. on behalf of the Canadian Cardiovascular Society.This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).Hypertension, which affects nearly 6 million Canadian adults, is a leading risk factor for stroke, cardiovascular disease, kidney failure, atrial fibrillation, and dementia. 1,2Those at highest risk of developing complications of hypertension include the approximately one third of Canadians whose blood pressure (BP) remains above recommended BP targets, and the 10%-15% who are estimated to have treatment-resistant hypertension are at even greater cardiovascular risk. 3These statistics underscore the need for accessible and effective clinical care delivery to optimize control and avoid hypertension-mediated adverse health sequelae.
Provision of specialist hypertension clinical care is an important component of an overall BP control strategy.Hypertension specialists focus on the assessment and management of complex patients.The types of referrals seen by hypertension specialists include the following: resistant hypertension (BP that remains above target despite treatment with 3 antihypertensive medications at optimal doses including a diuretic), 4 ; refractory hypertension (uncontrolled BP despite 5 or more antihypertensive agents, including a long-acting thiazide-like diuretic and a mineralocorticoid receptor antagonist), 5 ; labile BP; autonomic dysfunction; and diagnosing and managing secondary hypertension.In addition, hypertension specialists often oversee 24-hour ambulatory BP-monitoring programs.
In many cases, evidence to guide care in complex hypertension is limited.7][8] In these settings, clinical experience is an asset, and access to specialized resources, or lack thereof, may influence clinical decisionmaking and outcomes.
As little is known about the current state of specialist hypertension practice in Canada, we identified and surveyed hypertension experts in major Canadian hypertension centres, with the aim of better characterizing practice patterns, available resources, populations served, and services provided.

Ethics approval
Ethics approval was obtained from the University of Alberta before initiating study procedures (#Pro00120239).Details regarding informed consent were provided to each potential respondent, and consent was implied by completion of the survey.

Identifying hypertension specialists
To identify adult hypertension specialists and hypertension centres, we identified the Directors of the Divisions of traitent l'hypertension.M ethodologie : Un sondage a et e men e auprès de sp ecialistes de l'hypertension adulte de l'ensemble du Canada afin de d ecrire les centres de traitement de l'hypertension et la pratique des sp ecialistes au Canada, notamment les el ements suivants : la population de patients prise en charge par des sp ecialistes de l'hypertension, les renseignements sur la façon dont les soins sont prodigu es, les variations dans les habitudes de pratique ainsi que les diff erences relatives à l'accès aux ressources sp ecialis ees en hypertension à l' echelle du pays.R esultats : Le taux de r eponse au sondage a et e de 73,5 % dans 25 centres de l'hypertension.La plupart des r epondants etaient des n ephrologues et des sp ecialistes en m edecine interne g en erale.Les centres de l'hypertension recevaient entre 50 et 2500 patients par ann ee.En moyenne, 17 % (AE 15 %) des patients provenaient du service des urgences et 52 % (AE 24 %) provenaient d'une unit e de soins primaires.La plupart des centres avaient accès à des tests sp ecialis es (pr elèvements veineux surr enaliens, etudes du sommeil de niveau 1, tests autonomes) et à des traitements avanc es pour l'hypertension r esistante (d enervation r enale).Une h et erog en eit e consid erable a et e constat ee en ce qui concerne la pression art erielle cible chez les jeunes pr esentant un faible risque cardiovasculaire et les algorithmes diagnostiques pour etudier les causes secondaires de l'hypertension.Conclusions : Ces r esultats r esument la situation actuelle des soins sp ecialis es de l'hypertension et font ressortir des occasions d'accroître la collaboration entre les sp ecialistes de l'hypertension, notamment en ce qui concerne une normalisation de l'approche des soins sp ecialis es pour les patients hypertendus.
Endocrinology, Nephrology, General Internal Medicine, and Cardiology at each Canadian University with an affiliated medical school, through an Internet search.We e-mailed the divisional directors, asking them to identify one hypertension specialist (if any), defined as the physician to which complex hypertension referrals were directed, per division, and per major hospital or community clinic site (if more than one site was present).Each divisional director was sent 2 reminders if no response was received.
Identified hypertension experts were then contacted by email and invited to complete an online questionnaire.Each clinician was sent 2 reminders to complete the survey.Participating hypertension experts were invited to be coauthors of this article but were not otherwise offered additional incentives.

Survey development and dissemination
The survey (Supplemental Appendix S1) was internally created, tested for face validity, and revised by 4 authors (S.L., L.D., R.P., J.R.).The survey was sent in September 2022, through SurveyMonkey, via e-mail to the identified hypertension specialists.One physician of each specialty in each hypertension clinic completed the survey.Survey content included the following information related to the respondents' practice:

Statistical analysis
Descriptive statistics, including calculation of mean (standard deviation), median (interquartile range), counts and percentages, were used to collate and report the survey results.Missing data were excluded from the analysis; missing data occurred in up to 6 respondents for some questions.

Results
The initial request for identifying hypertension experts was sent to 63 divisional directors across Canada.Twenty responses were received, and 34 hypertension experts from cardiology, endocrinology, nephrology, and general internal medicine were identified and contacted via e-mail.Twentyfive of 34 (73.5%) completed the survey (Table 1), including respondents from Vancouver (n ¼ 4), Surrey (n , and Quebec City (n ¼ 1) across 25 sites (Fig. 1).Surveys were sent to providers in the Maritimes, but responses were not received.One questionnaire was completed only partially and was excluded from the analysis.Therefore, a total of 25 surveys were included in the analysis.
The primary subspecialties of respondents included nephrology (n ¼ 10), general internal medicine (n ¼ 8), endocrinology (n ¼ 4), and cardiology (n ¼ 3).The number of half-days per clinic dedicated each week to providing care to patients with hypertension ranged from 1 to 10, with a median of 3.

Service providers
The number of healthcare providers working per site ranged from 1 to 23 (median 3; interquartile range 1-6).At least one certified hypertension specialist (certification from the American Hypertension Specialist Certification Program, formerly the American Society of Hypertension (ASH) Hypertension Specialists Program) was working in 15 of 25 (60%) of the responding centres.Three (12%) of the surveyed sites were community sites.Many of the hypertension specialist centres (44%) were multidisciplinary and included at least one of the following: hypertension-trained nurses, pharmacists, kinesiologists, registered dieticians, and physiotherapists.Medical trainees, ranging from medical students to senior subspecialty residents, were present at 21 sites (84%).Educational experiences ranged from single clinics to multiple clinics in a block, to a longitudinal experience over months.

Service provision
Only one centre had Hypertension Centre Certification through the American Heart Association.Each centre was known for expertise in unique areas of hypertension, with some sites specializing in more than one area.Specifics regarding service provision are reported in Table 2.
Approximate wait times for initial consultation ranged from less than 1 month to 12 months; data for wait times are presented in Table 2. Two of the centres with 3-6-month wait times had one physician at the site seeing patients; the remaining sites with longer wait times had multiple physicians seeing patients at the site.Provisions were in place for urgent referrals at 24 of 25 centres.Timelines for urgent referrals are presented in Table 2. Catchment areas for care were also quite  Overall estimated patient volumes per year, per clinic, ranged from 50 to 2500 patients (24 respondents; mean 738 AE 972; median 425; interquartile range 800).The types of hypertension cases seen varied per site.One respondent did not answer this question, and overall response number was 20-24 depending on the type of hypertension.Results are reported in Table 2.

Specialized resources and services
Ambulatory BP-monitoring programs were available at 21 of 25 sites (84%), with the number of ambulatory BPmonitoring studies performed ranging from 0 to 2000 studies per year.A self and/or home BP-monitoring software platform for patients was available at 6 sites, with the Sphygmo Home software (mmHg Inc., Edmonton, Alberta) being the most frequently used, at 4 sites.
Adrenal vein sampling was available at 24 of 25 sites; the remaining site had access to adrenal vein sampling at another centre.For adrenal vein sampling, the success rate of sampling on the first try was estimated to be from 5% to 100% (22 respondents; mean 76% AE 24%).Hypertensive disorders of pregnancy were managed at 14 centres (56%); the remaining 11 centres referred these patients to another site.Device-based therapy and experimental treatments such as renal denervation were offered at 8 hypertension centres; 6 other sites made referrals to another centre for these therapies.Access to a level 1 sleep lab was available at 23 sites; those centres that did not have direct access referred patients to respirology for consideration of a level 1 sleep study (performed in a sleep laboratory).Level 3 sleep studies (performed in the patient's home) were accessible to 19 of the hypertension centres.Autonomic testing was available at 11 hypertension sites, and 6 other sites had access through other means (4 sites through cardiology; 2 sites through neurology).

Approaches to clinical care
Wide variations in practice were observed in clinical care delivery for primary hypertension and in the workup of secondary hypertension.Responses to clinical cases presented in the survey are provided in Table 3.

Quality improvement initiatives
All respondents completed questions about quality improvement.Nine respondents reported dedicated rounds to discuss hypertension topics and cases, with 6 sites convening rounds monthly, and 3 centres convening rounds yearly.Three centres tracked quality indicators on a systematic basis.BP control rates, medication adherence, adrenal vein sampling

Discussion
To our knowledge, this study is the first to examine practices of hypertension specialists across Canada.This survey provides a cross-section of specialist hypertension care in Canada, covering many hypertension centres.
These survey results demonstrate significant variability in hypertension specialist clinical practice views in Canada.This finding is not surprising given the lack of high-quality data in patients with complex hypertension and secondary hypertension and the variability in recommendations in clinical practice guidelines.
Our findings are similar to those of previous surveys assessing physician attitudes and practices in hypertension in other countries.A previous survey of cardiologists, internists, and general practitioners in the US studying pharmacologic treatment of hypertension with clinical cases found that despite most respondents being in agreement with established hypertension guidelines from the Joint National Committee, significant differences were present across specialties in choosing drug classes to treat hypertension, with cardiologists being more likely to choose angiotensin-converting enzyme inhibitors and calcium-channel blockers compared to internists and family physicians. 9Our survey is too small to determine whether the type of subspecialty training has a significant impact on practice patterns among hypertension specialists in Canada.
Another cross-sectional questionnaire surveying resident physicians in internal medicine, family medicine, and surgical specialties in the US about treatment of inpatient hypertension also found that although the majority of trainees based their management on Joint National Committee hypertension guidelines; respondents were divided on how they chose to manage asymptomatic, moderately elevated BP as an inpatient, with 44% starting an antihypertensive medication, and 56% deciding not to initiate pharmacologic treatment. 10lthough both studies focused on primary hypertension, they highlight the discrepancies between treatment guidelines and clinical practice, which were seen in our study also.We expected such discrepancies, specifically for complex cases of hypertension including secondary and resistant hypertension, as no consensus on management has been reached.
Potential reasons for practice pattern variation were not specifically addressed in our survey.A dearth of information is available in the literature for many of the clinical scenarios addressed in our survey, and for other scenarios, the literature presents variability.For example, 56% of respondents treat young patients with uncomplicated stage 1 hypertension with pharmacologic therapy once health behavior is optimized, whereas the others would wait for higher BP readings.This variability in practice is reflected in the variability among hypertension guidelines.For example, the 2017 American College of Cardiology and American Heart Association hypertension guidelines, and the 2018 European Society of Cardiology and European Society of Hypertension guidelines both suggest treatment if BP !140/90 mm Hg in all adult patients. 8,11However, in patients without cardiovascular risk factors, Hypertension Canada recommends initiating treatment if BP !160/100 mm Hg. 6 The number needed to treat for this average-risk population is high, which explains the higher Hypertension Canada threshold, whereas other guidelines offer simplified thresholds and targets. 12pecialists in this study reported seeing patients with primary hypertension, secondary hypertension, resistant hypertension, orthostatic hypotension, and autonomic dysfunction.Many of these conditions are common.For example, resistant hypertension is estimated to affect 10% of treated patients with hypertension in the primary care setting. 13Using traditional biochemical criteria for primary aldosteronism (PA), prevalence has been reported at 4.8%-16.6%,but with a more liberal biochemical definition, the prevalence could be as high as 13.8%-24.5%. 14Although this level of prevalence is reported for PA, a Canadian study found that the detection and treatment of expected PA cases is less than 1%. 15This study suggests that a system-level approach to assist with investigation and treatment of PA could be effective in closing gaps in care and improving clinical outcomes. 15Based on the estimated prevalence of these conditions, most patients with complex and secondary causes of hypertension are likely to be managed exclusively by primary care and by other specialist colleagues, rather than in specialized hypertension centres.
Another unknown is what factors influence referral patterns to hypertension specialist clinics, and which patients are best served in these clinics.The availability and wait times for hypertension specialist care vary across the country, as do resources, including allied-health professional availability.Given the well described disparities in hypertension control rates by sex, race, ethnicity, and other socioeconomic factors, 16,17 an important consideration is whether access to hypertension specialist care in Canada is equitable.Furthermore, a quarter million Canadians have resistant hypertension in Canada 3 ; consideration of how to meet the needs of this growing population given the existing clinic volumes reported in this survey will be needed.In internal medicine residency programs, ambulatory care exposure is limited, 18 which is where most hypertension care occurs.Heterogeneity in training experiences may explain some of the heterogeneity in practice patterns.More work is needed to better define whether patients are getting the right care at the right time delivered by the right provider.
This study also highlights opportunity for future work to describe hypertension control rates at each centre, choice of pharmacotherapy at each centre, and factors influencing the choice.We also found some survey responses that were unusual (Table 3) and warrant follow-up questions; perhaps more clarity is needed in the survey questions.This survey did not have the option of text to explain the answers provided.Given that the majority of hypertension care occurs in primary care, further surveys of primary care providers on the provision of hypertension care would augment this work.
To improve and standardize care delivery nationally, survey participants indicated interest in having case conferences on a variety of topics, including causes of secondary hypertension (renovascular disease, primary aldosteronism), autonomic dysfunction and orthostatic hypotension, and medical and interventional approaches to treatment-resistant hypertension.The Canadian Hypertension Specialists Society (CHeSS) recently created a virtual forum for these presentations.Survey participants also proposed topics for standardized protocols and evidence-based summaries on secondary causes of hypertension.The results of this survey, the renewed energy for ongoing learning by responding clinicians, and the recently published worsening hypertension control rates in Canada between 2007 and 2017 1 are impetus to continue efforts to raise awareness of hypertension, improve clinician education, and improve both access to care and hypertension control rates in Canada.
Several limitations of our study need to be considered.We were unable to identify a hypertension expert at every medical schooleaffiliated Canadian university, which may reflect the lack of hypertension specialist availability and/or be related to our method of identifying specialists.Our method of identifying experts through academic centres may miss those specialists who are not known to the divisional directors, including those practicing in the Yukon, Northwest Territories, and Nunavut, where no specialists were identified.Our e-mails were sent in English, which may have limited the responses provided by noneEnglish speaking hypertension experts.
An alternate sampling method of reaching out to only to physicians certified through the American Hypertension Specialist Certification Program may miss those specialists who do not have this certification.In addition, clinical case scenario responses represent the practice pattern of the individual responding on behalf of the centre and may not represent the practice patterns of all healthcare providers at each centre.Furthermore, respondents were asked to estimate the percentages reported here; thus, they may not be a true representation of the respondent's practice.

Conclusion
In this survey of hypertension specialists across Canada, we found significant variability in practice patterns.We found a keen interest among clinicians in sharing ideas and case discussions and the desire to distill ideas and create guidance statements and position papers in clinical situations for which little guidance is available beyond expert opinion.
variable and ranged from a portion of one city, to half a province, to several provinces.

Figure 1 .
Figure 1.Distribution of Canadian hypertension specialists who responded to our survey.

Table 1 .
Demographics of respondents to hypertension survey

Table 2 .
Service provisionClinics with areas of specialization (some clinics have more than one area of specialization)

Table 3 .
Approaches to clinical careSurvey questionSurvey responses 30-year old male patient with primary hypertension (work-up done for secondary causes all negative); optimized in terms of health behaviors; ABPM 145/92 mm Hg; no target organ damage; no comorbid medical conditions